Malaysia and Vietnam say there is no sign of a missing Malaysian airliner in the area where Chinese satellite images showed potential debris floating in the water.
The two countries sent search planes over the area in the South China Sea on Thursday, but officials said they did not find anything.
China released the images Wednesday, with state media saying they showed three fairly large objects near the plane's original flight path toward Beijing.
Meanwhile, the Wall Street Journal reported Thursday that U.S. investigators suspect the Malaysia Airlines plane remained in the air for four hours after passing its last known location over the Gulf of Thailand.
The report said the belief is based on data that is automatically sent by the plane's engines to the ground, and suggests the aircraft could have flown for an additional 4,000 kilometers.
Ships and aircraft from 12 countries are involved in a sprawling search that covers 93,000 square kilometers in the waters on both sides of Malaysia. An extra four hours in the air would put the plane far outside the search area, reaching potentially into areas of the Arabian Sea, Indian Ocean or Pacific Ocean.
There were 239 people on board Flight 370 when it disappeared Saturday less than an hour into a trip from Kuala Lumpur to Beijing.
Malaysian air traffic controllers did not receive any messages indicating the plane may have been in trouble, and said their communications with the pilots were routine.
Malaysia's military said Wednesday its radar had picked up signs of what could have been a jet flying to the west of the country over the Malacca Strait about an hour after the last contact with Flight 370. If the radar data is from the Malaysian Air flight, the plane would have taken a sharp westward turn to reach that area.